Changing an HID light bulb is not the same as changing a conventional light bulb. HID -- high-intensity discharge -- bulbs produce more lumens per watt than ordinary light bulbs. These lights are usually found in industrial, commercial and transportation settings, but they are also used for flood lighting and other residential lighting tasks. HID lights use metallic salts that are vaporized within the bulb. Because of the bulb's intensity it burns extremely hot, thus one must take more care when changing an HID light bulb.
Leave the light fixture off for at least 30 minutes before touching the HID bulb. These bulbs take much longer to cool than traditional bulbs, so let the bulb cool completely to avoid injury.
Remove the tempered glass covering, if applicable. Not all fixtures will have this component, but if yours does, remove the screws or clasps that hold the cover in place and remove it from the fixture.
Unscrew the HID bulb in a counterclockwise motion using a towel or cloth glove to remove it. Never handle these bulbs without a hand-covering as oils can damage the overall light fixture.
Screw the new bulb into your fixture with a clockwise motion, again using a towel or glove. HID bulbs are fragile so be careful not to over-twist when inserting.
Reattach any glass covering and turn on light to test. Leave the light on for at least 30 minutes the first time. HID bulbs must reach full temperature the first time they are turned on.